First of all welcome to TravelPunk!
I am not sure who told you that Malta is not very scenic, but it most certainly is. As far as which one to choose, they are both beautiful. Malta has a lot more diversity as regards historical sites, countryside and beaches and such. On the other hand there will be a ton of tourists there during the summer months. Tuscany will be quiet in comparison and you can go for long beautiful drives (if you rent a car) or walks. Really just depends on you. Malta has a lot more to offer in my opinion, but during summer it can be crowded on the beaches and big tourist spots.